#product_category_menu{
}

.sub-product_category_menu-title{  /*各カテゴリタイトルに関する指定*/
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin: 0 0 1px;
    padding: 6px 4px 8px 8px;
    font-size: 16px; /*文字サイズの指定*/
    font-weight: bold; /*文字の太さの指定*/
    font-weight: normal;
    color: #49382a; /*文字の色の指定*/
    letter-spacing: 0.01em;
    background: #fff; /*背景色の指定*/
    border-bottom: solid 1px #e5e5e5;　/*枠線色の指定*/
    text-decoration: none;
}

.sub-product_category_menu-title span{ /*親階層の指定*/
    font-size: 10px;
    letter-spacing: 0;
    color: #49382a;
    font-weight: normal;
}

.sub-product_category_menu-wrap { /*子階層の指定*/
    display: block;
    font-size: 13px;
    margin:0px 0px 18px;
    background-color: #fff;
}

.sub-product_category_menu-wrap input  {
    display: none;
}

.sub-product_category_menu-btn{ /*開くボタンの指定*/
    position: relative;
    display: block;
    flex-grow: 1;
    width: 100%;
    padding: 10px 22px 10px 8px;
    text-align: left;
    line-height: 1.6;
    color: #555;
    border: none;
    border-bottom: 1px solid #e5e5e5;
    background-color: inherit;
    cursor: pointer;
    box-sizing: border-box;
    transition: .3s;
}

.sub-product_category_menu-btn:hover {
    background-color: #fff;
    border-bottom: 1px solid #e5e5e5;
    font-weight:bold;

}

.sub-product_category_menu-btn:before { 
    position: absolute;
    top: 11px;
    right: 9px;
    font-size: 13px;
    color: #888;
    /*font-family: "Font Awesome 5 Free";*/
    content: '+';
    font-weight: bold;
    transition: .3s;
}

.sub-product_category_menu-btn:hover:before,
.sub-product_category_menu-btn:focus:before{
    color: #333;
}

.sub-product_category_menu-ul {
    display: block;
    margin:0px;
    padding: 0px;
    height: 0;
    opacity: 0;
    transform: translateX(-5px);
    background-color: #fafafa;
    list-style: none;
    transition: .0s;
}

.sub-product_category_menu-wrap input:checked + .sub-product_category_menu-ul {
    display: block;
    height: auto;
    opacity: 1;;
    transition: .1s;
    transform: translateX(0px);
}

.sub-product_category_menu-ul li{
    margin:0px;
}

.sub-product_category_menu-list{
    display: block;
    padding: 8px 6px 8px 22px;
    color: #666;
    border-bottom: 1px solid #d2d2d2;
    text-decoration: none;
    pointer-events: none;
}
.sub-product_category_menu-list:hover{
    background-color: #f5f5f5;
    font-weight:bold;
}

input:checked + .sub-product_category_menu-ul .sub-product_category_menu-list{
    pointer-events: auto;
}

.sub-product_category_menu-wrap .fas{
    padding-right: 4px;
}

<!-- ボーダー -->

.sub-product_category_menu-btn__open a,
.sub-product_category_menu-btn a,
.sub-product_category_menu-btn__open > span,
.sub-product_category_menu-btn > span {
  display: flex;
  align-items: center;
  width: 100%;
  padding: 5px 20px 5px 5px;
  border-bottom: #eee 1px solid;
  text-decoration: none;
  position: relative;
  font-size: 13px;
  height: auto;
}

.sub-product_category_menu-btn__open a:before,
.sub-product_category_menu-btn a:before {
  content: "";
  display: block;
  position: absolute;
  bottom: -1px;
  left: 0;
  width: 0;
  height: 1px;
  background: #888;
  -webkit-transition: all .4s ease;
  -moz-transition: all .4s ease;
  transition: all .4s ease;
}
.sub-product_category_menu-btn__open a:hover:before,
.sub-product_category_menu-btn a:hover:before {
  width: 100%;
}